Magnetoresistance of a ferromagnetsemiconductor interface. Pdf giant negative magnetoresistance in a nonmagnetic. At constant voltage bias, current increases by nearly one million percent upon application of a 2 t field. Review of hall effect and magnetoresistance measurements in. A platform is also provided for placing the sample and mounting the four probes on it. Colossal magnetoresistance materials, to which manganites and conventional ferromagnetic semiconductors belong, draw great attention because of their intriguing physical properties and the excellent prospects for their practical applications in electronic devices. Novel experimental setup to study the magnetoresistance of. It allows one to extract the carrier density and, in combination with resistivity measurements, the carrier mobility typically, the extraordinary hall effect is stronger than the. Magneto resistor definition, working, types, and applications. Magnetoresistance an overview sciencedirect topics. Under the action of the external electric field e e, 0, 0 r, through the semiconductor sample flows a current i.
The phenomenon of transverse magnetoresistance will be observed in an extrinsic semiconductor. The effect occurs in semiconductor metal hybrid systems when a. Organic magnetoresistance and spin diffusion in organic semiconductor thin film devices markus wohlgenannt department of physics and astronomy and optical science and technology center, university of iowa, 205 north madison street, 126 iatl, iowa city, iowa 52242, usa received 27 march 2012, revised 15 may 2012, accepted 21 may 2012. Spin hall magnetoresistance smr is a transport phenomenon that is found in some electrical conductors that have at least one surface in direct contact with another magnetic material due to changes in the spin current that are present in metals and semiconductors with a large spin hall angle. In addition, magnetic semiconductors are basic materials for hightemperature.
Experiments show that the application of a magnetic field increases the resistivity of a semiconductor and produces a decrease in the magnitude of the hall. The effects of material properties on resistance and magnetoresistance mr for an externallyshunted vdp plate in both probe configurations are presented. For example, in devices made from the prototypical small molecule alq3 omar reaches values of 10% or more at room temperature. A method is proposed for measuring the physical magnetoresistance, the resistivity, and the hall coefficient of semiconductor samples of orthogonal form.
Magnetic miniband structure and quantum oscillations in lateral semiconductor superlattices m. Universal properties of linear magnetoresistance in strongly disordered semiconductors h. Review of hall effect and magnetoresistance measurements in gaas materials and devices. Quantum linear magnetoresistance 791 where is the background dielectric constant due to ion cores, v is the electron velocity the spectrum is. Electric field induced suppression of the magnetoresistance of dilute magnetic semiconductor trilayers z. Experiment results to compatible with the conventional semiconductor technology, we fabricated transistor by implanting boron and large magnetoresistance discovered in nonmagnetic semiconductors offers an alternative route to renew magnetoelectronics without ferromagnets. Sep 10, 2014 a tunnelling anisotropic magnetoresistance tamr has been previously reported in devices with an antiferromagnetic afm metal electrode on one side and a nonmagnetic metal on the other side of. Based on ab initio calculations, we associate the origin of the phenomenon with large anisotropies in the relativistic electronic structure. Feb, 20 the extraordinary magnetoresistance emr effect is a change in the resistance of a device upon the application of a magnetic field in hybrid structures, consisting of a semiconductor and a metal. Defectdriven extreme magnetoresistance in an imnv semiconductor junjie yang,1 aaron wegner,1 craig m.
In previous work fesi has been doped with co, mn, p, and al. Macdonald department of physics, the university of texas at austin, austin, texas 78712, usa dated. It is shown that in a weak magnetic field the transport coefficients exhibit non. New kind of magnetoresistance has implications for semiconductor industry posted on january 10, 2018 january 11, 2018 by roopa sukumaran berzins scientists at the university of minnesota, in collaboration with researchers from pennsylvania state university have discovered the existence of magnetoresistance in topological insulatorferromagnetic. Indium antimonide, an example of a high mobility semiconductor, could have an electron mobility above 4 m 2 v. Wo2001041214a1 extraordinary magnetoresistance at room. Magnetoresistance of ntype magnesium germanide iowa state. Extraordinary magnetoresistance effect in semiconductor. Four probe arrangement, sample, magnetoresistance setup. Scattering mechanisms of the hall effect and transverse.
Their faraday rotation can be up to six orders of magnitude higher than that of nonmagnetic semiconductors. This model permitted to explain satisfactorily all the data obtained in 7. Colossal magnetoresistance and phase separation in. Brown,2 and despina louca1,a 1department of physics, university of virginia, charlottesville, virginia 22904, usa 2center for neutron research, national institute of standards and technology, gaithersburg, maryland 20899, usa received 16 may 2018. Jan 10, 2018 new kind of magnetoresistance has implications for semiconductor industry posted on january 10, 2018 january 11, 2018 by roopa sukumaran berzins scientists at the university of minnesota, in collaboration with researchers from pennsylvania state university have discovered the existence of magnetoresistance in topological insulatorferromagnetic. Theory of magnetoresistance in the anderson localised. Magnetocapacitance and magnetoresistance near room. Magnetoresistance of the square a and the sinai billiard b for the temperatures 30 mk bottom, 0. In these materials the electrical resistance can be changed several. Fesi is a narrowgap 650k semiconductor which exhibits similar properties to the class of 4f compounds known as kondo insulators.
Extraordinary magnetoresistance effect in semiconductormetal hybrid structures jian sun in this dissertation, the extraordinary magnetoresistance emr effect in semiconductor metal hybrid structures is studied to improve the performance in sensing applications. Valleydependent magnetoresistance in twodimensional semiconductors akihiko sekine and allan h. Extraordinary magnetoresistance effect in semiconductormetal hybrid. Extraordinary magnetoresistance emr is a geometrical magnetoresistance effect discovered in 2000, where the change in electrical resistance upon the application of a large magnetic field can be greater than 1,000,000% at room temperature orders of magnitude greater than other magnetoresistance effects such as gmr and cmr. Pdf extraordinary magnetoresistance in semiconductormetal. Magnetoresistance depends on the spin precession angle in a quantum well channel.
We obtain theoretical formulas by solving the corresponding electrodynamic boundary value problem. The silver chalcogenides are narrowgap semiconductors 6, so conventional theories predict that the magnetoresistance should saturate at large fields, unlike what is observed. The arrays of magnetinthe semiconductor nanostructures show semiconductor type transport properties with magnetoresistance typical. Universal properties of linear magnetoresistance in.
A spectacular anisotropy observed in cu is explained based on the nonspherical fermi surface of this metal in this chapter. Magnetoresistance in semiconductormetal hybrids for power. A theory of mixed electronicimpurity phase separation in degenerate magnetic oxide semiconductors, including hight c superconductors and materials with colossal magnetoresistance cmr, is. Giant unidirectional magnetoresistance in topological. Recent studies in devices comprising metal antiferromagnets have demonstrated the feasibility of a novel spintronic concept in which spindependent phenomena are governed by an antiferromagnet instead of a ferromagnet. Enhanced roomtemperature geometric magnetoresistance in. Coherent spin precession is obtained by injection into the side of a quantum well. Theory of the magnetoresistive effect in semiconductors.
Heiman1 1department of physics, northeastern university, boston, ma 02115 2department of mechanical engineering, northeastern university, boston, ma 02115 3department of chemical engineering, northeastern university, boston, ma 02115. June 1, 2018 we show theoretically that twodimensional directgap semiconductors with a valley degree of freedom. A very large magnetoresistance effect was discovered in the early nineties in manganese oxides which was coined colossal magnetoresistance cmr 4, 5. Magnetic field can also be used to cause the metal to semiconductor transition, a phenomenon also called colossal magnetoresistance. In these materials the electrical resistance can be changed several orders of magnitude by application of a large magnetic field. Hall coefficient and magnetoresistance of semiconductors. Constant energy ellipsoids for a many valley semiconductor. Germanium is a typical electronic semiconductor with a cubic lattice. Magnetoresistance mr in general is nonzero and anisotropic. Abstract the use of magnetic fields in the electrical characterization of semiconductor materials is familiar to everyone in the.
Magnetoresistance overview janicenickel computerperipheralslaboratory hpl9560 june, 1995 magnetoresistance, sal, dualstripe, spinvalve, gmr magnetoresistance, the change of a materials resistivity with the application of a magnetic field, is a well known phenomenon. We are going to treat the magnetoresistance of metals in a quite general and simple manner. To explain the origin of the magnetoresistance, a twoband model for conduction in a magnetic semiconductor diode was developed based on the mott model applied. Measurement of magnetoresistance of semiconductors. Pdf anisotropic magnetoresistance in an antiferromagnetic. Magnetic oscillations found in the susceptibility also manifest themselves in magnetoresistance at low temperatures. In the presence of the intrastate interaction, a magnetic field suppresses two types of the hopping process. Pdf magnetoresistance effects in hybrid semiconductor. The dependence of the magnetoresistance on applied magnetic field will be determined and compared to theoretical predictions. Organic magnetoresistance and spin diffusion in organic. Two prototype metal semiconductor hybrid topologies for power applications have been derived from emr sensor technology and are examined here for the first time, the shunted corbino plate. The magnetoresistance due to the variablerange hopping conduction is calculated by the critical path method in the andersonlocalised regime of semiconductors taking into account the electronelectron interaction. One million percent tunnel magnetoresistance in a magnetic. The extraordinary magnetoresistance emr effect is a change in the resistance of a device upon the application of a magnetic field in hybrid structures, consisting of a semiconductor and a metal.
Department of electrical and electronic engineering, tokyo institute of technology, 2121 ookayama, meguro, tokyo 1520033, japan. Measuring the magnetoresistance of orthogonal semiconductor. Vertical longitudinal magnetoresistance of semiconductor. We report a synthesis of colloidal nanostructures combining a magnetic material fept with a narrowgap semiconductor pbs and pbse in form of core. Room temperature operation is implemented by utilizing spin drift and diffusion. High tunnel magnetoresistance based on 2d dirac spin gapless. The insets show a scanning electron micrograph and dimensions of the device. University research center, wright state university, dayton, ohio 45435. To observe the phenomenon of magnetoresistance in a semic onductor and study the magnetic eld dependence of the transverse magnetoresistance of a given semiconductor sample. This vlmr occurs when the electrons occupy the open fermi surface and their motion. More recent discoveries are the giant magnetoresistance gmr 2,3, the colossal magnetoresistance cmr 4,5, the tunnel magnetoresistance tmr 6, the extraordinary. Extraordinary magnetoresistance in semiconductormetal. For inhomogeneities of sufficiently large diameter relative to that of the.
Applying on the sample the magnetic field b 0, 0, b r, a potential difference uh, called hall bias, appears between its lateral faces, on the direction normal to both e r. Magnetoresistance, the property of a material where its electrical resistivity changes when exposed to an external magnetic. Anisotropic magnetoresistance in an antiferromagnetic. The underlying principle of this phenomenon is a change of the current path in the hybrid structure upon application of a magnetic field, due to the lorentz force. Magnetoresistivity can now depend on magnetic field, angle, and. Giant gatecontrolled proximity magnetoresistance in. Pdf tunneling conductance and magnetoresistance of. A semiconductor material carrying current develops an electromotive force, when. Nov, 2003 the resistance of a homogeneous semiconductor increases quadratically with magnetic field at low fields and, except in very special cases, saturates at fields much larger than the inverse of the.
Extraordinary magnetoresistance effect in semiconductormetal hybrid structures jian sun in this dissertation, the extraordinary magnetoresistance emr effect in semiconductormetal hybrid structures is studied to improve the performance in sensing applications. Magnetic semiconductors strong magnetooptical effect allows the material to be used in optical modulators. Magnetoresistance in semiconductor metal hybrids for power applications presented by clay nunnally, a candidate for the degree of doctor of philosophy and hereby certify that, in their opinion, it is worthy of acceptance. The effect is observed as a decrease in the electrical conductivity corresponding to increases in the applied magnetic field. In other words, the flow of electric current through the magneto resistor changes when an external magnetic field is applied to it. Towards observation of magnetoresistance due to spin transport, we show that the dop ing pro. The transverse magnetoresistance of the inmnas layer was measured in magnetic fields up to 1 t and in the temperature range of 1961 k. New kind of magnetoresistance has implications for. Nonsaturating magnetoresistance in heavily disordered. Jul 29, 2005 magnetocapacitance and magnetoresistance near room temperature in a ferromagnetic semiconductor. The gaussmeter operates on the principle of hall effect in semiconductors. Enhanced roomtemperature geometric magnetoresistance in inhomogeneous narrowgap semiconductors s.
Selfsimilar magnetoresistance of a semiconductor sinai. This is the influence of impurities in semiconductors. The junction magnetoconductance with magnetic field and current parallel is welldescribed by an analytical expression for the total conductance g tot for the two spin split bands 1. Semiconductors are good for testing theory because they offer another dimension for measuring resistivity. To observe the phenomenon of magnetoresistance in a semiconductor and study the magnetic eld dependence of the transverse magnetoresistance of a given semiconductor sample. Magnetoresistance of inmnas magnetic semiconductors. Magneto resistor is a type of resistor whose resistance changes when an external magnetic field is applied. Following the recent observation of large magnetoresistance at room temperature in poly. Magnetoresistance is modulated by exploiting spin hall and rashba effects. The extraordinary magnetoresistance emr effect is a change in the resistance of a device upon the application of a magnetic field in hybrid structures. Vertical longitudinal magnetoresistance of semiconductor superlattices. The magnitude of the effect in materials used in the recording industry has.
Giant unidirectional magnetoresistance in topological insulator ferromagnetic semiconductor heterostructures. Dowell associate professor of electrical and computer engineering. Request pdf high tunnel magnetoresistance based on 2d dirac spin gapless semiconductor vcl 3 future spintronic devices on the nanoscale require lowdimensional materials with high spin. Rosslerrecent citations transport properties of r0. Valleydependent magnetoresistance in twodimensional.
Extraordinary magnetoresistance in semiconductormetal hybrids. The magnetoresistance for temperatures below 19 k has been previously reported for this sample where a negative magnetoresistance of 0. Rogado dupont central research and development, experimental station, p. Vertical longitudinal magnetoresistance vlmr caused by the peculiar shape of the fermi surface of a superlattice has been observed in gaasalxga1xas superlattices. Plots of magnetoresistance versus magnetic field at four different temperatures are shown in. Extraordinary magnetoresistance effect in semiconductormetal. For the case of a positive magnetoresistance the junction conductance will decrease with increasing magnetic field, whereas for a negative magnetoresistance it will increase with field.
579 925 1029 1015 1136 1570 357 922 676 186 732 480 242 648 187 232 1327 310 1536 1277 90 444 1510 1584 1277 241 301 1438 26 111 1339 1372 241 922 342 251 425 504 752 1430 697 328 1436 703 971 638 1166